DESCRIPTION: Anger and anger management style (the tendency to suppress or express anger) are important emotional factors which contribute to the aggravation of chronic pain. Few mechanisms, however, have be examined which explain how anger variables affect chronic pain. A "symptom-specificity model" is advanced in which chronic low back pain (CLBP) patients can be distinguished from patients with chronic nonback pain and from normals on the basis of anger-induced tension in the musculature at the site of pain (lower paraspinals). The investigator proposes that exaggerated lower paraspinal (LP) reactivity during anger constitutes a physiological mechanism by which anger and anger management style affect CLBP. Three aims will be pursued. First, it will be determined whether anger provocation has unique effects on LP reactivity among CLBP patients. Study 1 will examine whether CLBP patients show: greater overall LP reactivity than nonback pain patients and normals; greater LP reactivity during anger-induction versus anxiety-induction; trapezius, bicep and cardiovascular reactivity equivalent to the other groups. Second, it will be determined whether anger expression or suppression have effects on LP reactivity. Study 2 will examine whether self-reported anger management style predicts the degree to which anger is expressed during provocation, which in turn predicts LP reactivity, but not trapezius nor bicep reactivity, only among CLBP patients. Third, it will be determined whether anger arousal can influence variables reflecting CLBP aggravation via LP reactivity. Study 3 will test whether anger-induced LP reactivity, but not trapezius nor bicep reactivity, is related to pain report and pain behavior among CLBP patients during a subsequent pain-induction task. Findings will show whether LP reactivity constitutes a unique pathway by which anger, distinct from other emotions, exacerbates CLBP. Documenting a link between anger and LP reactivity will give empirical justification for targeting problematic anger among CLPB patients, and will provide principles on which to found new intervention strategies.